The invention relates to a rail guidable conveying device and apparatus for conveying printed products, of the type disclosed in CH 382768 and GB 966,402. In such prior apparatus, a plurality of conveying devices fixed to a rail grip the printed products, convey them along the rail and deposit them at a remote location.
WO 99/33730 discloses a conveying system which can be used in the manner described in WO 99/33731, and which comprises a guide part, which is of V-shaped design in the conveying direction, a carrying part, which is fixed to the guide part and is intended for retaining a product, and a coupling part, which is configured such that it can be coupled to a drive means. Examples of drive means used are continuously driven bodies or elements which are moved in the conveying direction and transmit a magnetic force to the conveying devices, or the coupling parts thereof, from stationary magnets arranged along the movement path. In the case of the known conveying means, the coupling part is fixed to the guide part. The strength of the coupling is thus determined predominantly by the strength and arrangement of the magnets. At locations at which a pronounced forward movement of the conveying device is desired, magnets are arranged relatively closely together and/or relatively strong magnets are provided, while fewer magnets, or no magnets at all, are provided at other locations, e.g. in the region of a buffer storage section.
The above described prior conveying devices are problematic when different conveying speeds are to be realized at the same location of the movement path, in particular when conveying devices are to be stopped temporarily and then conveyed further individually or as a group at the original speed. It is indeed known to block the continuing movement of the conveying devices mechanically by restraining elements in order to realize a buffer storage section. However, on account of the coupling remaining unchanged, mechanical wear is produced by the carrying-along effect of the drive means, as a result of which the coupling and the state of the restraining element may be impaired in the long term. In order to reduce the wear-inducing force, it is known to arrange fewer magnets in the region of a buffer storage section. This has the disadvantage, however, that the operation of conveying the conveying devices further as the restraining element is removed likewise takes place only with reduced force and thus at a slower speed.
The object of the invention is thus to provide a conveying device and a conveying apparatus in which the abovementioned disadvantages are avoided and it is possible to park or buffer-store the conveying devices with the lowest possible level of wear and to convey them further without being slowed down significantly.
The above and other objects and advantages of the invention are achieved by the provision of a rail guidable conveying device for conveying sheet like products, and which comprises a guide part, a carrying part which is arranged on the guide part, and a coupling part which can be coupled to a drive means. The coupling part is configured such that the strength of the coupling to the drive means is variable. It is thus possible to change the advancing force by adjustment of the conveying device, preferably by mechanical action by means of obstructions which are located in the movement path and may be, for example, restraining elements or other conveying devices which have already been stopped. The mechanical components involved are therefore exposed to less wear. Furthermore, the coupling can be reproduced at full strength without any significant time delay.
In the case of a conveying apparatus according to the invention, use is likewise made of conveying devices having a coupling part which allows the coupling strength to be varied. The conveying apparatus preferably has at least one switchable restraining element which is arranged in the region of the movement path of the conveying devices. The restraining element can stop the conveying devices by acting on the coupling part, on the guide part or on the carrying part. The coupling part here is preferably designed such that the restraining element acting thereon causes the coupling strength to be reduced, e.g. by it moving the coupling part away from the drive means.
The invention achieves higher flexibility in the case of conveying apparatus, in particular in respect of the individual movement and stoppage of conveying devices, since the change in the advancing force, rather than having to be carried out on the conveying apparatus itself, takes place on the conveying devices. The invention advantageously makes it possible, using the same conveying apparatus, for the conveying devices both to be transported with a high conveying force and to be buffer stored at any desired locations of the movement path with a low level of wear and a low restraining force. The coupling to the drive means can be reproduced, according to the invention, largely without any time delay, with the result that individual conveying devices can rapidly be transported further following the stoppage. For this purpose, it is advantageous if, rather than the coupling being reduced to zero during the stoppage, a residual conveying force acts even in the buffer stored state. Furthermore, it is then also possible for a number of conveying devices which have been moved up against one another in a buffer storage section to be conveyed further as a block.
In order to change the coupling mechanically, the coupling part can be moved relative to the guide part between at least a first and a second position, the coupling being weaker in the second position than in the first position. For this purpose, the coupling part is connected, for example, pivotably to the guide part or is suspended in a floating manner on the guide part. With force being applied to a first surface, which is preferably oriented in the conveying direction, a second surface, which is directed toward the drive means, is moved. This varies the spacing in relation to the drive means and thus the coupling.
Each conveying device preferably may be coupled magnetically to the drive means, the coupling part in this case at least partially consisting of ferromagnetic material. By virtue of the spacing between the coupling part and the drive means being changed, it is easily possible to change the strength of the coupling.
In a preferred configuration of the conveying apparatus, the conveying devices are driven via magnetic force, with magnets being arranged in a stationary manner in the region of the movement path and driving taking place by moving the drive means which transmits the magnetic force to the conveying devices. The magnetic coupling may be increased, in principle, by a suitable configuration of flux parts, which are connected to the drive means. This has the advantage that, in principle, a high conveying force can be realized with the same magnet strength, it being the case that, in the regions in which a lower conveying force is desired, e.g. in buffer storage sections, the coupling is reduced by action according to the invention on the conveying devices or coupling part thereof.